[time-nuts] Generating a solid PPS from 10Mhz source
alan.melia at btinternet.com
Mon Jan 18 13:33:10 EST 2016
Indeed Bob in the 70s I built a failure diagnostic equipment to record the
Idd of a chip as a function of a position of a spot of light scanning the
surface. The intensity was very low and not optimum wavelength.......it was
a scope raster demagnified by using a microscope camera accessory backwards.
The intensity was modulated and the signal detected on a PSD and displayed
on a modified Robot SSTV receiver.....but it showed just how senstive chips
are to light.
----- Original Message -----
From: "Bob Camp" <kb8tq at n1k.org>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Monday, January 18, 2016 3:11 PM
Subject: Re: [time-nuts] Generating a solid PPS from 10Mhz source
> Back in the 70’s I was involved in making LCD watches. The whole “photo”
> issue had not been fully through through. One day our chief marketing guy
> the project was driving around in Phoenix AZ. He looks down and notices
> his watch is dead. Pops out a spare, puts it on, confirms it it working.
> Hangs his arm out
> the window and …. that one is dead as well.
> We changed the die coat on the ASIC to an opaque version soon after that …
> Light does indeed interact with semiconductors. It happens even on
> circuits that
> you would not *think* are photo sensitive. Physics is nasty that way ….
>> On Jan 18, 2016, at 6:45 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>
>> In message <569BC23A.3030400 at arcor.de>, Gerhard Hoffmann writes:
>>> LEDs abused as References:
>> This is one of the most stupid ideas ever, because LEDs works both ways.
>> (Back when LED wrist-watches first came out, people soon discovered
>> that they would reset themselves when photographed with flash.)
>> If you insist on using LEDs as voltage references, the first thing
>> you need to do is to dip the LED in something which shields it 100%
>> from incoming light *including infrared*
>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
>> phk at FreeBSD.ORG | TCP/IP since RFC 956
>> FreeBSD committer | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by
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